Does anyone have any experience with gaseous urea injection in FLUENT? I'm working on urea injection in a boiler furnace (SNCR) and confused with my result. First I calculate flow field with urea injection, but when I switch to FLUENT NOx calculation module and set SNCR properties, I don't get good result. It seems that urea injection has absolutely no effect on my NOx reduction! While the urea is completely consumed, but my NOx out flow rate (from stack) doesn't show any change. In addition, during solution I see only the plot of urea and HCN residuals; while there are other pollutants in the legend (located at top left of residual window) like as NH3, N2O, HNCO and NCO, but there is no residual plot for them (I select all of them in my equation list). Their values are also zero when checking them on their graphical contours. It seems that fluent does not calculate the rate equation for them!!!